1. Field of the Invention
The present invention relates to a process for producing large quantities of heartcut distillate resin precursors. More particularly, the present invention is directed to a two-stage process for the production of heartcut distillate. Specifically the present invention is directed to a two-stage heartcut distillate process wherein the first stage involves hydrogenation of a hydrocarbon oil composed primarily of two-ring aromatic molecules to form large quantities of partially saturated naphtheno-aromatic molecules and the second stage involves subjecting the hydrogenated oil to a steam cracking process under conditions which favor producing a heartcut distillate containing an amount greater than 4 wt.% yield of heartcut distillate resin precursors.
2. Discussion of Background and Material Information
Heartcut distillate (HCD) resin precursors are an important and valued by-product of ethylene production by steam cracking. These precursors are reactive aromatic molecules, examples of which include styrene, vinyl-toluene, indene and methyl indene. Yields of HCD resin precursors produced by using conventional cracking processes on standard feedstocks vary from 1-4%.
Catalytic hydrogenation is a process well-known in the art used for the improvement in the petroleum refining process. It has been applied to a variety of precursor feeds that are intermediates in various stages of refining including heavy petroleum fractions, asphaltene-rich feeds, aromatic-rich fractions and dripolene light-gas oils to improve the production of hydrocarbon oil products, alkenylbenzene compounds, and other products useful to the art, for example, as disclosed in U.S. Pat. Nos. 3,689,401; 3,692,858; 3,844,932; and 4,565,620. Catalytic hydrogenation is also used prior to thermal steam cracking in a two-step process known in the art as an efficient means of producing olefins as disclosed in U.S. Pat. No. 4,188,281 light olefins, as disclosed in U.S. Pat. No. 4,500,416, and monoaromatic hydrocarbons as disclosed in U.S. Pat. No. 4,022,681.